1. Field of the Invention
The present invention relates to a sending method of pay contents in a communication system having plural radio terminals which carry out communication through predetermined communication network (e.g., radiotelephone network or the like) using a predetermined first communication scheme (e.g., CDMA scheme or the like) and which carry out peer-to-peer communication using a predetermined second communication scheme (e.g., infrared communication, communication adhering to Bluetooth standards), and having a carrier which carries out communication using the first communication scheme between the terminals. The invention also relates to a radio terminal and a carrier suitable for the sending method.
2. Description of the Related Art
Examples of data transfer system using short-range radio between terminals are                cashless system between a cellular phone and an automatic dispenser using infrared communication IrDA (100 kbps or less),        data exchange between personal computers and backup using radio LAN (IEEE802.1X, 50 Mbps or less), and        photograph transfer between cellular phones using Bluetooth (1 Mbps or less).        
Especially in the widely used cellular phones, high-speed transfer carried out between cellular phones has appeal for consumers who want to share information with their associates. However, due to low speed of a radio channel and competition with carriers, the high-speed transfer has not been in common use.
To solve such a problem, there is provided a sending/receiving system of contents using the peer-to-peer communication (ad hoc communication) (e.g., see Japanese Patent Application Laid-open No.2003-333079 (JP-A) and JP-A 2002-209028.
JP-A 2003-333079 discloses a system in which a radio terminal receives commercial contents which advertises contents from a sending server which sends contents, and if the radio terminal sends the commercial contents to another radio terminal, the sender radio terminal receives a discount coupon that can be used when buying the contents advertised by the advertising contents.
JP-A 2002-209028 discloses a system in which when contents are sent to an ending terminal from a starting terminal through an ad hoc network, a relay terminal is interposed between the starting terminal and the ending terminal. In the system, the starting terminal sends the contents to the relay terminal, the relay terminal sends the contents to the ending terminal, and the relay terminal charges a fee for the service against the starting terminal and the ending terminal.
In the system disclosed in JP-A 2003-333079, however, even a terminal outside the range of the sending server which sends contents can receive advertising-contents from a radio terminal (radio terminal A) which received the advertising contents directly from the sending server, but the radio terminal outside the range of the sending server is not managed by the sending server, and it is not possible to grasp to which radio terminal the advertising contents were sent. That is, the system of 2003-333079 can be used only as a sending system of advertising free contents. In the case of sending pay contents, this system has a problem in terms of safety when the contents are sent and in terms of authenticity of radio terminals other than the radio terminal A which receives contents directly from the sending server.
The system of JP-A 2002-209028 only charges a fee for service of relay of the relay terminal in the direct communication between radio terminals. Since there is no function to grasp the entire system, it is difficult to prevent pay contents from being dispersed or distributed without limitation.